*The ignition advance curve, in general, is quicker yet shorter than an engine without a supercharger, this helps give better throttle response until the boost pressure kicks in. The advance curve most seen is an initial timing of 18 degrees with a total of 32 degrees; this is just a starting point and must be tailored to each engine. MSD can supply a boost retard ignition system, which allows an advance curve that can supply enough advance to give good throttle response yet, as the boost comes in, it can retard the timing to avoid detonation. The boost retard system can retard the timing from 1 to 3 degrees per pound of boost and total retard can be as much as 20 degrees. A vacuum advance should only be used in a low boost application and should be limited to 10 degrees of advance with engine vacuum above 10 to 12 inches of vacuum. The best way to check and set the advance curve is on a distributor test stand, then confirm the results with an advance timing light.